Sealing for a regulable coolant pump

ABSTRACT

A regulable coolant pump for a coolant circuit of an internal combustion engine, which has a pump housing and a hollow shaft that is placed in the housing and mounted on rolling bearings that connects a drive wheel to an impeller. As the impeller rotates, coolant is drawn in via an inlet chamber that is upstream from the cover disk and is delivered, via vanes of the impeller, into an annular channel of the pump housing. The volumetric delivery can be influenced through an axially displaceable baffle plate assigned to the impeller. The baffle plate is connected in a rotationally rigid manner to a push rod guided in the hollow shaft that acts together with an adjusting unit. A sealing element is provided to seal an annular gap that forms between the baffle plate and the cover disk.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority of DE 10 2010 022 884.2 filed Jun. 7, 2010, which is incorporated by reference herein.

FIELD OF THE INVENTION

The invention is directed to a regulable coolant pump for a cooling circuit of an internal combustion engine.

BACKGROUND OF THE INVENTION

Radial flow pumps are used preferably as coolant pumps for internal combustion engines. After startup of the internal combustion engine, in order to attain the operating temperature in as short a time as possible it is advantageous to prevent the coolant from circulating in a forced manner. For the purpose of influencing the volumetric delivery of coolant pumps, it is known to vary the drive rotational speed of the impellers or to insert a control or regulating valve before or after the coolant pump in the coolant circuit. The regulation of the volumetric delivery enables the warm-up phase of the internal combustion engine to be shortened and, at the same time, frictional losses and emission values can be reduced.

Known from U.S. Pat. No. 1,813,747 A is a radial pump wherein the volumetric delivery can be regulated by means of a slide, which is disposed on the impeller and is displaceable in the axial direction. The regulation of the slide between an open position and a closed position is effected by turning a thread-type guide, which adjusts the slide axially.

DE 10 2004 054 637 A1 discloses a regulable coolant pump wherein a valve having an associated valve slide is displaceable between two end positions within the pump housing by a magnet coil.

According to DE 100 57 098 C1, a regulable coolant pump comprises a magnet coil that acts together with an armature disk, which is disposed on the drive shaft so as to be rotationally fixed, but displaceable under spring loading. In dependence on frictional linings, via which the impeller is connected to the armature disk, driving of the impeller is effected when the magnet is de-energized.

SUMMARY OF THE INVENTION

The invention is based on the object of disposing a baffle plate for a regulable coolant pump such that the coolant pump does not deliver any coolant, a zero delivery being realizable.

Therefore, the invention relates to a regulable coolant pump for a cooling circuit of an internal combustion engine. The coolant pump has a pump housing in which there is a hollow shaft that is mounted on rolling bearings and that connects a drive wheel to an impeller. The impeller, which is connected to an inlet chamber, has an axially displaceable baffle plate. The axially displaceable baffle plate can influence a volumetric delivery of the coolant pump. For this purpose, the baffle plate is connected to an adjusting unit via a push rod guided in the hollow shaft.

To ensure a zero delivery when the baffle plate is in the closed state, it is provided, according to the invention, that a sealing element is provided between the cover disk and the baffle plate. The sealing element in this case is disposed such that an effective sealing ensues between the components, the cover disk and the baffle plate and, furthermore, owing to an elastic deformation of the sealing element, no annular gap is formed between these components. By means of this measure, unlike former solutions—setting of the delivery rate via the gap dimensions between the cover disk and the baffle plate in the closed state—it is possible, advantageously, to achieve an actual zero delivery rate in all operating ranges of the internal combustion engine. The elastic sealing element advantageously compensates tolerances of the mutually supported components that are associated with their production or caused by thermal expansion. The fully sealed annular gap according to the invention prevents the coolant, not yet warmed to operating temperature, from circulating after the startup of the internal combustion engine. The thereby shortened cold running phase and more rapid attainment of the operating temperature reduce the period for heating the passenger compartment, reduce the friction and, consequently, result in a saving of energy.

According to a preferred development of the invention, it is provided that, for the purpose of sealing the ensuing annular gap, the elastic sealing element is disposed in the greatest diameter region of the cover disk. When the coolant pump is closed, the sealing element is supported in a sealing manner on the baffle plate.

For this purpose, the sealing element can be disposed, for example, in an end face groove or in an outer stepped region of the conically widened portion of the cover disk. According to an alternative disposition, the sealing element surrounds the conical portion of the cover disk on the outside. A further possibility is for the sealing element to be inserted in an outer stepping of the conically widened portion that is directed toward the cover disk.

Irrespective of the mounting position and fastening of the sealing element, the latter is disposed in alignment with an inner wall of the cover disk when the coolant pump is open. Consequently, the sealing element does not cause either a disadvantageous flow resistance or influencing of the flow.

The sealing element, or the seal, is preferably realized as a multicomponent injection molded part. A highly elastic, wear resistant plastic is preferably provided as material for the sealing element. As an alternative to a single piece structure, the invention includes a reinforced sealing element, wherein the reinforcement is, for example, pressed into a groove of the cover disk and vulcanized to a sealing material.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features of the invention are given by the following description, in which an exemplary embodiment is presented. In the figures:

FIG. 1 shows a sectional view of the structure of a coolant pump configured according to the invention;

FIG. 2 shows, in an enlarged representation, a portion from FIG. 1, which illustrates the mounting position of the sealing; and

FIG. 3 shows a representation corresponding to FIG. 2, wherein the sealing has been elastically deformed.

DETAILED DESCRIPTION OF THE DRAWINGS

A coolant pump 1, represented in a longitudinal section, is shown in FIG. 1. The structure comprises a pump housing 2, in which a hollow shaft 3 is mounted on rolling bearings and connects an impeller 4 to a drive wheel not represented in FIG. 1. When the coolant pump 1 is in the operating state, the coolant flows axially, via an inlet chamber 5, to the impeller 4 and is routed radially, via the vanes 6, into an annular channel 7. A cover disk 8 of the coolant pump 1 constitutes a transition region to the inlet chamber 5. For the purpose of influencing the volumetric delivery of the coolant pump 1, an axially displaceable baffle plate 9 is assigned to the impeller 4. The baffle plate 9 is fixed in position on a push rod 10, which is guided in the hollow shaft 3 and which, at the end that faces away from the impeller 4, is operatively connected to an adjusting unit, in particular an electromagnet, not represented in FIG. 1. By means of the adjusting unit, the baffle plate 9 can be set between the end positions, or any intermediate positions. According to FIG. 1, the baffle plate 9, when in an end position, is supported directly on the impeller 4. In this position, the baffle plate 9 blocks an inlet 11, and thereby a coolant inlet into the annular channel 7. For the purpose of achieving a zero delivery of the coolant pump 1 when the baffle plate 9 is in this position, a sealing element 14 is provided to seal an annular gap 13 that forms between the cover disk 8 and the baffle plate 9. The sealing element 14, preferably realized as an elastic seal, is disposed in a greatest circumferential region of the cover disk 8 and is supported directly on the baffle plate 9. A further end position, which, at the same time, enables a maximum volumetric delivery of the coolant pump 1, ensues when the baffle plate 9 bears on the back wall 12 of the impeller 4.

FIGS. 2 and 3 illustrate the mounting position and action of the sealing element 14. FIG. 2 shows the sealing element 14, which, over an outer portion, is supported, almost in linear contact and without elastic deformation, on the cover disk 8. This representation illustrates a corresponding, aligned position between the course of an inner wall 16 of the conically widened portion 15 of the cover disk 8 and the sealing element 14, which position, advantageously, does not negatively affect the coolant flow when the coolant pump 1 is open. The sealing element 14 in this case is inserted in an end-face, outside stepping 17 from the portion 15 of the cover disk 8, and is thereby fixed in position in a form-closed and/or material-closed manner.

FIG. 3 shows the sealing element 14 having been elastically deformed radially outward in the operating position, for the purpose of realizing a zero delivery of the coolant pump 1. Made clear in this case is the capacity to adapt to the surrounding construction and the possibility of compensating production and/or temperature related tolerances of the sealing element 14, which, at least according to the radial deformation, enables a longitudinal compensation corresponding to the dimension S. Furthermore, FIG. 3 shows that, owing to the elastic deformation of the sealing element 14, a gap dimension 18 between the housing 2 and the cover disk 8 is sealed at the same time.

REFERENCE NUMERALS

1 Coolant Pump

2 Pump Housing

3 Hollow shaft

4 Impeller

5 Inlet Chamber

6 Vane

7 Annular Channel

8 Cover Disk

9 Baffle Plate

10 Push Rod

11 Inlet

12 Back Wall

13 Annular Gap

14 Sealing Element

15 Portion

16 Wall

17 Stepping

18 Gap Dimension 

1-7. (canceled)
 8. A regulable coolant pump for a coolant circuit of an internal combustion engine, comprising: a pump housing having an inlet chamber and an annular channel that functions as an outlet of the pump; a cover disk arranged in a transition region of the inlet chamber; an impeller having vanes arranged in the inlet chamber, a rotation of the impeller draws in a coolant from the inlet chamber, and delivers the coolant into the annular channel of the pump housing; a hollow shaft mounted in the pump housing for rotating the impeller; a push rod guided in the hollow shaft and axially movable therein; an axially displaceable baffle plate, which is connected to the push rod and acts to open and close the annular channel; and a sealing element, which seals an annular gap between the baffle plate and the cover disk.
 9. The regulable coolant pump according to claim 8, wherein the sealing element is supported in a sealing manner on the baffle plate and integrated in a region of the cover disk having a greatest diameter when the coolant pump is closed.
 10. The regulable coolant pump according to claim 8, wherein the sealing element surrounds a conically widened portion of the cover disk on an outside face of the conically widened portion.
 11. The regulable coolant pump according to claim 10, wherein the sealing element is inserted in an outer stepping of the conically widened portion of the cover disk, and the stepping is directed toward the cover disk.
 12. The regulable coolant pump according to claim 8, wherein the baffle plate is positioned at least in an offset manner in relation to the cover disk and the sealing element is disposed in alignment with an inner wall of the cover disk when the coolant pump is in an open state.
 13. The regulable coolant pump according to claim 8, wherein the sealing element is a multicomponent injection molded part.
 14. The regulable coolant pump according to claim 8, wherein a the sealing element is comprised of an elastomer. 